A rare cosmic explosion has given astronomers an unprecedented look at a massive star in its final moments, revealing a missing link between ordinary stellar explosions, so-called supernovae, and gamma-ray bursts, the brightest and most powerful phenomena in the Universe.
The event, named EP260321a, was first detected by the Einstein Probe satellite as a brief flash of X-rays from a galaxy about 500 million light-years away. Scientists interpret the signal as a "shock breakout," the moment when the shock wave from a star's collapsing interior bursts through its surface and releases the first light of a supernova.
Shock breakouts are thought to occur in every massive star's death, but they're notoriously hard to catch. They last only a short time and shine brightest in X-rays. In the past two decades, astronomers have confidently identified just one other clear X-ray shock breakout, making EP260321a an exceptionally rare find.
